Pressure responsive device for actuating an alarm



March 19, 1968 c. H. PEEK ET AL 3,374,323

PRESSURE RESPONSIVE DEVICE FOR ACTUATING AN ALARM Filed April '7, 1966 2Sheets-Sheet 1 4 flyi 3d 37 23 26 25 36 22 29 52 1/ J5 272/36 24 L! i /l2/ 22} A L42 /0 4e 47 Q 50 45 4a Inventors Ceci/ H peck Kinney; R Peek M4ttorneys March 19, 1968 c. H. PEEK ET AL 3,374,323

PRESSURE RESPONSIVE DEVICE FOR ACTUATING AN ALARM Filed April 7, 1966 2Sheets-Sheet 2 Inventors A Horneys United States Patent 3,374,323PRESSURE RESPONSIVE DEVICE FOR ACTUATING AN ALARM Cecil H. Peck andKenneth R. Peek, both of 2 Russell Drive, Stanwell, Middlesex, EnglandFiled Apr. 7, 1966, Ser. No. 540,865 Claims priority, application GreatBritain, Apr. 14, 1965, 16,123/65; Jan. 11, 1966, 1,333/66 7 Claims.(Cl. 20083) ABSTRACT OF THE DISCLOSURE A pair of panels defining aheremtically sealed cavity placed under a controlled air pressure andhaving a switching means associated therewith which is responsive to apredetermined change in the air pressure to actuate an extemal circuitsuch as a relay alarm system.

This invention relates to alarm apparatus.

The present invention is alarm apparatus comprising two panels sealinglyunited together and entrapping therebetween a space or cavity whereinthe pressure is less than atmospheric and holds inoperative a switchdevice in an electric circuit incorporating alarm means, said switchdevice being adapted to react to operate the alarm means on equalizationof the pressures.

The present invention is also alarm apparatus comprising two panels orlaminations entrapping therebetween a space or cavity wherein thepressure is less than atmospheric and holds inoperative in an electricalcircuit incorporating alarm means a switch device adapted to react tooperate the alarm means on increase by a predetermined amount of thepressure in said space or cavity, said switch device comprising a pairof plates spaced apart at their peripheries by an insulating and sealingmedium, one of said plates having a central outwardly-projecting studproviding an axial tapped through opening for adjustment of a threadedpin terminating in the space between the plates in a contact opposinganother contact proud of a diaphragm secured at its periphery adjacentthe other plate by said medium.

One of the panels may be a window and the other a strip of glasssealingly united together at the periphery of the strip with a space orcavity between the two, a small hole in the panel or the strip locatingthe switch device. Such a window could form part of a door, or couldform a door such as a showcase door.

The two panels could form a partition wall, a window, a door, a floor,or a ceiling, or could be incorporated in a wall, a window, a door, afloor, or a ceiling.

The panels may be sheets of polyvinyl chloride or other plasticsmaterial, or ferrous or non-ferrous metal, and the sealing together ofthe panels may be effected by heating, soldering, welding, adhesive,cement or other sealant, depending on the material or materials used.

Where one of the panels is a strip there is no need to provide spacingmeans between the panels to keep the panels separated under vacuum, butif the areal dimensions of both panels are such that further support isdesirable to keep the panels separated under vacuum spacing means in theform of small spacer elements may be disposed between the panels,preferably in a uniform pattern. The spacer elements are preferablybonded to at least one of the panels, and they may have openings thereindefining between the panels spaces in which air is trapped on evacuationof air from between the panels, thus affording further support to thepanels. The spacer elements could be of disc-shape of say A diameter andW thick. They may be of, say, PVB (a name applied in the trade to asealing material which is a polyvinyl butyl resin containing, as aplasticiser, triethylene glycol di-Z-ethyl butyrate) or of Teflon orMakrolon. Teflon is a trade name for polytetrafluoroethylene andMakrolon is a trade name for a thermoplastic polycarbonate of 4,4 -d1-hydroxy-diphenyl-Z,Z-propane (-biphenol A).

The spacer elements could be replaced by wire netting, porous rigid foammaterial, or porous, corrugated sheet material, or one or more of thepanels may 'be dimpled thus to obviate the need for spacer elements orwire netting. Where desirable a combination of any two or all three ofthe spacing means aforesaid may be used.

Where it is necessary to circumvent an obstacle projecting from asurface to which apparatus according to the invention is to be applied,for example a light rose on a ceiling or an electric switch on a wall,the two panels sandwich a bag of nylon, polyvinylchloride, or otherplastics material capable of supporting a vacuum of up to six or seveninches of mercury. The bag is held open by a porous foam sheet or bysuitably positioned porous pipes, or by other means such as a corrugatedsheet of porous plastics material, all with the object of ensuring thatthe bag will not collapse under vacuum. Manifestly, the bag closes offthe space between the panels where confronting the obstacle.

It will be manifest that, because of the vacuum in the space between thepanels, the diaphragm is in contact centrally with the plate. The closedswitch completes a circuit which holds inoperative a relay controllingan alarm system, but immediately the vacuum is destroyed the switchopens and releases the relay, whereby the alarm is operated.

The invention can be used in ceilings, walls, floors, windows and doors,indeed anywhere subject to entry by force from without.

Embodiments of the invention will now be described,

H by way of example with reference to the accompanying drawings, inwhich:

FIG. 1 is a sectional view of two panels united together, positivelyspaced apart, with the outer of the two mounting a switch device andproviding for communication of a pipe with the cavity between thepanels;

FIG. 2 is a similar view, on an enlarged scale, particularlyillustrating the switch device; p

FIG. 3 is a view similar to FIG. 2, but particularly illustrating thepipe communication with the cavity;

FIG. 4 is a view similar to FIG. 1, illustrating a modification;

FIG. 5 is a plan view illustrating the use of the FIG. 4 construction;

FIG. 6 is a sectional view at right angles to that of FIG. 4 and to anenlarged scale, illustrating another modification; and

FIG. 7 is a diagrammatic illustration of an installation where severaldouble-panel structures are connected in series to a single vacuum pumpand reservoir.

Referring now to the drawings, throughout which like parts are denotedby like reference numerals, two panels 10 and 11 of polyvinyl chlorideor other plastics material entrap therebetween a space or cavity 12 inwhich is located spacing means in the form of wire netting 13. Thepanels are of convenient size for the purpose intended and are tailoredto suit the surface or part-surface to which the composite structure isto be applied, the outside surface 14 of the inner panel 11 being thenadjacent to the first-mentioned surface or part-surface and beingadhered thereto in any convenient manner. The panel 10 has a peripheralflange which fits about the panel 11 and a sealing compound such asepoXy-polysulphide is provided between the panels at the peripheriesthereof as shown at 101, and also externally of the panel 11 betweensame and the flange 100 as shown at 102.

Referring now particularly to FIG. 2 the outer panel has a hole formedtherein and the tapped stem 16 of a bush 17 is located in said hole. Thestem 16 has a peripheral groove 18 and the latter assists adhesion ofthe stem to the hole surround by means of a suitable adhesive orcementing compound such as Araldite (registered trademark). Alongitudinal groove 19 is formed in the stem adjacent the tapped opening20 and extends com pletely through the bush.

The switch device 21 comprises a disc-shaped base plate 22 with aperipheral flange 23 and a central threaded stud 24 which screws intothe tapped opening 20. The dimensions of the base plate 22 and the head25 of the bush 16 are such that a small clearance is left between theflange 23 and the periphery of the head, and an O-ring seal 26 coatedwith silicone grease is compressed in said clearance as the switchdevice is screwed into position. An outer circular plate 27 is held inspaced and parallel relation to the base plate 22 by an annular ceramicspacer 28 which both seals the space 29 between the plates and locatesin position a diaphragm 30 which has a central contact 31 of preciousmetal such as platinum proud of its surface opposed to the base plate22. A hole 32 is provided in the base plate 22 and is aligned with thegroove 19 so that the switch space 29 communicates with the space orcavity 12.

The stud 24 has a central tapped opening 33 with a fine thread and inthis is engaged a threaded pin 34 at whose end opposed to the diaphragmis a contact 35 also of precious metal such as platinum. The pin 34enables adjustment of the setting of the switch device. The plate 27 hastwo small holes 36 therein for engagement by a suitable tool whenassembling the switch device 21 to the bush 17. Care must be taken thatthe tool engages only to a limited extent in the holes 36 to avoiddamage to the diaphragm 30. Two brass pins 37 and 38 extend from thebase plate 22 and outer plate 27, respectively, and these serve forconnecting the switch device to a relay controlling an alarm system.

On the space or cavity 12 being evacuated to provide therein a vacuum ofthe order of, say, 2.5 inches Hg, the diaphragm 30 is pulled and thecontacts 31 and 35 close together. This locks the relay and the alarmsystem is inoperative. When the vacuum drops below a predeterminedvalue, say 2 inches Hg, the diaphragm 30 flexes outwardly and pulls thecontact 31 from the contact 35 breaking the electrical circuit andreleasing the relay, thus operating the alarm system.

The function of the wire netting 13 or other spacing means is to preventinward collapse of the panels when the space 12 is evacuated.

Referring now particularly to FIG. 3, the outer panel 10 has a secondhole formed therein and the tapped stem 46 of a second bush 47 islocated therein. The stem 46 has a peripheral groove 48 and the latterassists adhesion of the stem to the hole surround by means of a suitableadhesive compound or cementing compound such as Araldite. A pipe 49 hasa threaded end 50 by means of which it is screwed into the tappedopening in the bush 47, and the pipe 49 serves for evacuating the spaceor cavity 12. A flow-restricting sleeve 51 is fitted into the pipe 49close to the threaded end of the latter and this enables the evacuatingpump to compensate for any slight loss of vacuum due to leakage at thejunction between, on the one hand the bush 47 and the panel 10, and, onthe other hand the pipe end 50 and the bush 47.

Referring now particularly to FIGS. 4 and 5, the cavity or space 12between the panels 10 and 11 is occupied by a bag of nylon or otherplastics material which will support a vacuum of not less than 6 inchesHg. Flexible porous pipes 61 within the bag 60 prevent collapse of thebag under vacuum. This construction is especially useful when anobstacle is to be negotiated on a ceiling, wall, or the like, andreferring particularly to FIG. 5, a light switch 62 is shown on a wall63. The bag 60 is shaped to fit about the light switch 61 and, ofcourse, the panels 10 and 11 have suitable openings cut therein. Theedges of the bag walls about the shaped openings therein are sealedtogether and the space between the switch 62 and the double-panelstructure is filled with a sealing material such as epoxypolysulphide.It will be noted in FIG. 5 that the pipes 61 are bent to pass round theholes in the bag 60. The bag 60 may have an eyelet therein adjacent thelongitudinal groove 19 in the stem 16 of the bush 17, but alternativelyand preferably the connection with the switch 21 is effected in themanner now to be described with reference to FIG. 6.

In FIG. 6 the pipes 65 are of nylon and are not porous and are clippedbetween the panels 10 and 11 with the ends of .the pipes interconnectedby return-bends 66. The vacuum is in the pipes 65 and one end pipe isconnected to the switch 21 and the other either blanked off or connectedto an external pipe 49 in the same manner as will now be described forthe connect-ion to the switch 21. The appropriate end pipe 65 is formedadjacent its free end 67 with a neck 68 leading into a reduced diameter.The reduced-diameter end 67 is coupled to a pipe elbow 69 which includesa coupling part 70 engaged by a screw nut 71 acting on an olive 72 whichengages the wall of said end on tightening of the nut 71 and deformssaid wall as indicated at 73. The other limb of the elbow 69 extendsthrough a small hole 74 provided therefor in the panel 10 and is bothexternally threaded and internally tapped at its free end 80 besideshaving an intermediate peripheral ledge 75 with an out-turned flange 77which butts against the inner surface 76 of the panel 10. A look ring 78is screwed on to the free end 80 of the limb 69 externally of the panel10, and has slots 79 which are engaged by a peg spanner when this isbeing done. The remainder of the construction is as described withreference to FIG. 2 save only that a second O-ring seal 81, coated withsilicone grease and located by the flange 77 is compressed between theledge 75 and the surface 76. Manifestly, a groove such as 19 (FIG. 2)and a hole such as 32 (FIG. 2) are provided in the FIG. 6 construction,although not seen, to enable communication between the switch space 29and the cavity 12 between the panels 10 and 11.

In the adaption of the pipe connection to the switch just described tothe FIGS. 4 and 5 embodiment of the invention, the eyeletted hole in thebag 60 is traversed by the pipe elbow 69 and the eyelet is engagedbetween the flange 77 and the surface 76.

In the diagrammatic illustration in FIG. 7, several double-panelstructures 10A and 11A, 10B and 11B, and 10C and 110 are connected inseries to a vacuum reservoir with which is associated apressure-sensitive switch 91 adapted to switch on a motorised vacuumpump 92 if the vacuum in the main pipe 93 falls below a predeterminedvalue and switch off the pump when the vacuum regains the predeterminedvalue. As can be seen branches 49A, 49B and 49C, with flow-restrictingsleeves 51A, 51B and 51C fitted therein, communicate with the cavities12A, 12B and 12C between the various pairs of panels.

Double-panels forming part of alarm apparatus according to the inventionmay be fitted to walls, ceilings or floors by either adhesive or anyother suitable and known method. Double-panels fitted to walls andceilings may be covered by tiles or a layer of a plastics material, orhave any other suitable surface finish. Double-panels fitted to floorsmay be made of steel or other strong material and covered by cork orother suitable covering material.

We claim:

1. Alarm actuating apparatus comprising:

(a) first and second panels impervious to air;

(b) means interspacing said panels in parallel relationship andseal-ingly uniting them together along a closed peripheral path todefine between said panels a hermetically sealed cavity;

(c) means communicating with said cavity for estabiishing apredetermined air pressure less than atmospheric pressure in saidcavity;

(d) a housing mounted on one of said panels;

(e) openings extending through said housing and one of said panels;

(f) a diaphragm mounted in said housing with one face in communicationwith said cavity through two of said openings and the other face incommunication with atmosphere through another of said openings, a firstelectrical contact mounted on said diaphragm, a 'fixed adjustable secondelectrical contact mounted in said housing in alignment with said firstcontact, said diaphragm being movable in response to changes in saidpredetermined air pressure between a position wherein said contactsengage and a position wherein said contacts do not engage; and

(g) means on said housing for connecting an alarm means to saidcontacts, said alarm means adapted to be actuated upon said diaphragmattaining one of said positions.

2. Alarm actuating apparatus as set forth in claim 1,

wherein said housing comprises:

(a) first and second electrically conducting plates of similar arealdimensions and electrically connected to said alarm means;

(b) an insulating and sealing spacer joining said plates at theirperipheries and securing said diaphragm to said first plate; and

(c) said first and second plates each having an opening formed therein.

3. Alarm actuating apparatus as set forth in claim 2,

wherein said switching means further comprises:

(a) a bush having a tapped stem which partially plugs said two openings;

(b) a threaded stud projecting from one of said plates and engaging insaid tapped stem, said stud having an axial tapped bore opening intosaid housing and into said cavity; and

(c) a threaded pin engaging in said tapped bore and having an endentering said chamber, said second contact being mounted on said end.

4. Alarm actuating apparatus as set forth in claim 1, further comprisingan envelope of plastics material substantially filling said cavity, theinterior of the envelope being in communication with said means forestablishing said predetermined air pressure and with said one face ofthe diaphragm, and porous means in said envelope for preventing collapseof the envelope when evacuated.

5. Alarm actuating apparatus as set forth in claim 1, further comprisinga closed system of interconnected non-porous rigid pipes maintainingsaid panels in spaced relation, means connecting said system of pipeswith one face of said diaphragm, and means connecting said system ofpipes to said means for establishing said prede termined air pressure.

'6. Alarm actuating apparatus as set forth in claim 1, wherein saidmeans to establish a predetermined air pressure comprises a pipeentering one of said openings, and means for evacuating said cavitythrough said pipe, a flow restricting sleeve in said pipe, and apressure sensitive switch communicating with said pipe and energizingsaid means for evacuating said cavity when the vacuum in the pipe fallsbelow a predetermined level.

7. Alarm actuating apparatus comprising two panels sealingly unitedtogether to define therebetween a cavity wherein the pressure is lessthan atmospheric, a switch device adapted to operate an alarm means onincrease by a predetermined amount of the pressure in said cavity, saidswitch device comprising a pair of plates mounted on said panels, aninsulating and sealing medium spacing said plates apart at theirperipheries to form a switch space, said switch space being incommunication with said cavity, a central outwardly projecting stud inone of said plates and providing an axial tapped through opening, athreaded pin adjusta bly mounted in said opening and terminating in thespace between the plates in a first contact, and a diaphragm secured atits periphery adjacent the other plate by said medium and mountinganother contact at a position opposite said first contact, saiddiaphragm being movable responsive to a pressure increase in said cavityto open said contacts.

References Cited UNITED STATES PATENTS 1,684,530 9/1928 Bast 340-2291,974,779 9/ 1934- Lupold et a1 340-240 1,986,479 1/1935 Lowe et al.340-440 X 2,972,132 2/ 1961 =Putney 340-240 X FOREIGN PATENTS 706,1596/1931 France. 563,348 11/1932 Germany.

BERNARD A. GILHEANY, Primary Examiner. H. B. GILSON, Assistant Examiner.

